Question T7A07
From subelement T7 - T7A
What is the function of a transceiver’s PTT input?
Why is this correct?
PTT stands for Push-To-Talk, and the PTT input switches the transceiver from receive to transmit when grounded. This is the fundamental control that activates transmission mode. Option A is incorrect because CW (Morse code) uses a separate key input. Option C is wrong because PTT doesn't generate tuning tones. Option D is incorrect because PTT has nothing to do with preamplifier tuning. The PTT input is essential for voice operation and can be activated by pressing a microphone button or grounding the PTT line on the transceiver's accessory socket.
Memory tip
Remember PTT as the 'transmission trigger' - it's the universal switch that tells any transceiver 'start transmitting now.' Whether it's a handheld radio's mic button or an external PTT switch, the principle is always the same: ground the PTT line to transmit.
Learn more
In practical operation, understanding PTT is crucial for proper station control. The PTT input accepts control signals from various sources: microphone switches, foot switches, computer interfaces for digital modes, or external switching circuits. When building a multi-radio station, PTT sequencing becomes important to prevent simultaneous transmission. Many transceivers also provide PTT output signals to control external amplifiers or antenna switches, creating a coordinated transmission system that protects your equipment and ensures clean signal transmission.
Think about it
Why do you think the PTT input uses grounding rather than applying a positive voltage to switch to transmit mode?